The present disclosure generally relates to radar surveillance systems for detection and imaging of concealed individuals and objects and, more particularly, to adapting radio communication electronics and signals developed for wireless personal area and wireless video area networks (WPAN and WVAN) to ultra-wideband (UWB) radar ranging and imaging.
Ultra-wide band (UWB) technology has come into use for helping to satisfy an increasing demand for wireless communication at high data rates between a variety of personal computer (PC) and consumer electronics products. The WiMedia™ Alliance is a global nonprofit organization that defines, certifies, and supports wireless technology that enables multimedia data transfers at high-speed (480 mega-bits per second (Mbps) and beyond) with low power consumption in a wireless personal area network (WPAN). WiMedia's UWB technology offers end users wireless freedom and convenience in a broad range of PC and consumer electronics products. These products include Wireless USB™ docking stations, hard drives, projectors and laptop to HDTV (high-definition television) audio/video extenders. The WiMedia™ Alliance also focuses on providing specifications for streaming video applications. The WiMedia™ UWB common radio platform incorporates media access control (MAC) layer and physical (PHY) layer specifications based on multi-band orthogonal frequency division multiplexing (MB-OFDM) and operates in the 3.1 to 10.6 GHz UWB spectrum.
Also, there has recently been increasing demand for a wireless video area network (WVAN) for combining uncompressed high-definition video, multi-channel audio, intelligent format and control data, and “Hollywood”-approved standard content protection techniques. A core technology is based on the 60 GHz millimeter-wave frequency band, which promotes theoretical data rates as high as 25 gigabits per second (Gbps), permitting it to scale to higher resolutions, color depth, and range. Among 60-GHz communication standards that use OFDM are: IEEE 802.15.3c, ECMA 387, WiGig, and IEEE 802.11ad. The WirelessHD® Consortium is an industry-led effort to define a worldwide standard specification for providing solutions for WVAN networking. For end-users, elimination of cables for audio and video dramatically simplifies home theater system installation and eliminates the traditional need to locate source devices in the proximity of the display. The WirelessHD® specification has been architected and optimized for wireless display connectivity, achieving in its first generation implementation high-speed rates up to 4 Gbps at ten meters non-line-of-sight for consumer electronics, personal computing, and portable device products.
Like WiMedia™ UWB technology, the WirelessHD® PHY is also based on OFDM, with an instantaneous modulation bandwidth, however, that is three and half times greater than that of the WiMedia™ OFDM system. The requirement for high data throughput at distances of 10 meters requires a large allocated frequency spectrum. A large amount of spectrum is available on an unlicensed basis in many countries in the 60 GHz band. In North America and Japan, a total of 7 GHz in each country is allocated for use, 5 GHz of which is overlapping. The band 57˜64 GHz is allocated in North America while 59-66 GHz is allocated in Japan. In addition, Korea and the European Union have allowed similar allocations. The regulating agencies allow very high effective transmit power (the combination of transmitter power and antenna gain), e.g., greater than 10 Watts (W) of effective isotropic radiated power (EIRP). High EIRP and wide allocated bandwidth can allow high throughput connections that are, however, very directional.